Electronic device with flexible data and power interface

ABSTRACT

Electronic modules with small and flexible interfaces are disclosed. One example electronic module includes a power supply terminal configured to receive power for the electronic module and circuitry configured to carry out various functions. The functions carried out by the electronic module circuitry include simultaneously receiving both of the following via the power supply terminal: a power signal for carrying out a mission mode operation of the electronic module, and a data signal.

The present patent application is a divisional application of prior U.S.patent application Ser. No. 13/114,935, filed on May 24, 2011, byTimothy J. Warneck, titled “Electronic Device with Flexible Data andPower Interface,” which is a nonprovisional application of U.S. patentapplication Ser. No. 61/439,704, filed on Feb. 4, 2011, by Timothy J.Warneck, titled “Electronic Device with Flexible Data and PowerInterface,” which applications are hereby incorporated by reference intheir entirety, and priority thereto for common subject matter is herebyclaimed.

BACKGROUND

The present invention relates, in general, to measurement systems and,more particularly, to the measurement systems for electrical signals.

Electronic devices (also referred to herein as modules) typicallyinclude a relatively small number of terminals and each terminal istypically dedicated to a specific purpose. For example, certainelectronic modules have only a terminal dedicated for providing power tothe module, a terminal dedicated for providing ground, and a terminaldedicated for providing output data. No terminal is provided forinputting data to such modules. A small number of dedicated terminalsminimizes overall module size and simplifies the interface. Therefore,adding a new terminal for an additional purpose is undesirable,particularly if the additional purpose is not needed during mission modeoperations. Including a terminal that is useful only during aconfiguration mode operation is undesirable for a variety of reasons.For example, an additional terminal consumes valuable space andmaterials and increases interface complexity, which in turn increasesthe risk of confusion as to which terminal is which.

Programming an electronic sensor module with sensor calibration data isone example of a function for which an additional terminal might beneeded during only a limited portion of a module's lifetime. Electronicsensor modules and other similar electronic devices typically requiresome form of calibration of their output to compensate for incidentaldesign variations that occur during manufacturing or other changes thatoccur during operational use. Electrical calibration is performed, forexample, by first manufacturing the sensor module, stimulating thecompleted sensor module with a known stimulus, comparing the module'soutput with an expected output corresponding to the known stimulus, andrecording in a memory a table of calibration data that is thereafterreferenced by the sensor module when outputting sensor readings.Consequently, the sensor module is able to compensate for any variationsdetected with respect to the expected output corresponding to the knownstimulus. After the electronic sensor module is calibrated andperforming its sensing function, additional data input is rarely, ifever, required. Therefore, use of a dedicated terminal for enteringcalibration data is undesirable because the dedicated terminal wouldhave little use relative to other terminals while consuming valuablespace and materials and increasing interface complexity.

A variety of techniques exist for loading calibration data into anelectronic sensor module or other electronic module without using adedicated terminal. However, certain existing techniques requireintegration of overdriving circuitry into the electronic module, whichconsumes a large area and large amounts of power. Moreover, manyexisting techniques preclude or prevent any data from being output bythe electronic module while calibration data is loaded.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from a reading of thefollowing detailed description, taken in conjunction with theaccompanying drawing figures, in which like reference charactersdesignate like elements and in which:

FIG. 1 depicts a general embodiment of an electronic module with a smalland flexible interface;

FIG. 2 depicts a method of using the small and flexible interface of theelectronic module in FIG. 1 to configure the electronic module;

FIG. 3 depicts a second embodiment of an electronic module that is moredetailed than the general embodiment of FIG. 1;

FIG. 4 depicts a method of using the small and flexible interface of theelectronic module in FIG. 3 to configure the electronic module;

FIGS. 5A and 5B depict graphs of signaling levels at input and outputterminals of the electronic module of FIG. 3 during different modes ofoperation;

FIG. 6 depicts a third embodiment of an electronic module that is ableto transition modes without use of a timer;

FIG. 7 depicts graphs of signaling levels at input and output terminalsof the electronic module of FIG. 6 during different modes of operation;

FIG. 8 depicts a fourth embodiment of an electronic module thatconserves more power than the third embodiment of FIG. 6 with use of adetect enable signal;

FIG. 9 depicts a method of using the small and flexible interface of theelectronic module in FIG. 8 to configure the electronic module;

FIG. 10 depicts graphs of signaling levels within and at input andoutput terminals of the electronic module of FIG. 8 during differentmodes of operation; and

FIG. 11 depicts graphs of signaling levels within and at input andoutput terminals of an alternative timerless embodiment of theelectronic module of FIG. 8 during different modes of operation.

For simplicity and clarity of illustration, elements in the figures arenot necessarily to scale, and the same reference characters in differentfigures denote the same elements. Additionally, descriptions and detailsof well-known steps and elements are omitted for simplicity of thedescription. As used herein current carrying electrode means an elementof a device that carries current through the device such as a source ora drain of an MOS transistor or an emitter or a collector of a bipolartransistor or a cathode or an anode of a diode, and a control electrodemeans an element of the device that controls current flow through thedevice such as a gate of an MOS transistor or a base of a bipolartransistor. It will be appreciated by those skilled in the art that thewords during, while, and when as used herein are not exact terms thatmean an action takes place instantly upon an initiating action but thatthere may be some small but reasonable delay, such as a propagationdelay, between the reaction that is initiated by the initial action andthe initial action. The use of the words approximately, about, orsubstantially means that a value of an element has a parameter that isexpected to be very close to a stated value or position. However, as iswell known in the art there are always minor variances that prevent thevalues or positions from being exactly as stated. It is well establishedin the art that variances of up to about ten percent (10%) (and up totwenty percent (20%) for semiconductor doping concentrations) areregarded as reasonable variances from the ideal goal of exactly asdescribed.

DETAILED DESCRIPTION

Reference will now be made to the figures wherein like structures willbe provided with like reference designations. It is understood that thefigures are diagrammatic and schematic representations of presentlypreferred embodiments of the invention, and are not limiting of thepresent invention, nor are they necessarily drawn to scale.

Embodiments of electronic modules and methods of using such modulesdescribed herein provide, among other things, efficient use of input andoutput terminals, thereby decreasing interface complexity and circuitfootprint size. Moreover, certain embodiments provide full duplexbidirectional data communications with the module during a configurationor programming mode.

In an example embodiment, a sensor module includes a power supplyterminal configured to receive power for the sensor module and circuitryconfigured to carry out various functions. The functions carried out bythe sensor module circuitry include receiving an uncalibrated sensorsignal from a sensor and, via the power supply terminal, receiving bothpower and calibration data from a source external to the sensor module.The sensor module circuitry functions also include calibrating theuncalibrated sensor signal based on the received calibration data.

In another example embodiment, a method of configuring and operating asensor module includes, via a multi-use terminal on the sensor module,receiving both power and calibration data from a source external to thesensor module. The method further includes receiving an uncalibratedsensor signal from a sensor, calibrating the uncalibrated sensor signalbased on the received calibration data, and outputting the calibratedsensor signal via a data output terminal on the sensor module.

Although the description provided herein is primarily directed toembodiments of electronic sensor modules that output calibrated sensorreadings, application of the invention is not limited to use with or inelectronic sensor modules only. The sensor module embodiments of theinvention described herein are merely illustrative of certain benefitsof the invention. Those skilled in the art will appreciate that othertypes of electronic modules, including controllers, data loggers, or anyother device for which a remote control interface is desired can alsobenefit from the principles of the invention.

FIG. 1 is a schematic block diagram of an electronic module 100 inaccordance with a general embodiment of the present invention. Themodule 100, which may be a single integrated circuit, a circuit boardassembly with discrete components, or a combination thereof, has aninterface to external circuitry comprising three terminals: a powersupply and data input (i.e., multi-use) terminal 110, an output terminal120, and a ground or reference voltage terminal 130. Although the module100 is illustrated as having only terminals 110, 120, and 130, thevertical ellipses 140 represent that the module may include any positiveinteger (one or more) of terminals which may be configured as digitalonly, analog only, or switchable between digital and analog, dependingon the module's design and/or operation mode. In certain embodiments,however, the terminals do not include a dedicated data input terminaland/or the number of terminals is limited to three to simplify theinterface and make a highly self-contained module. In this descriptionand in the claims, a terminal means any input terminal, output terminal,or input/output terminal of the module, regardless of the physical formof that terminal. Thus, a terminal can be a conductive pin thatprotrudes, a contact pad, an inductive terminal, a radio frequencyterminal, or a terminal of any other type that is capable of receivingand/or transmitting control, data, or power as a digital or analogsignal. The principles of the present invention are not limited in anyway to the form of the terminals, and thus the term “terminal” should bebroadly construed. Moreover, where reference is made herein to voltagesignals, equivalent signals, such as current signals, inductive signals,radio frequency signals, etc., can be used instead.

As with the other circuit drawings provided herein, FIG. 1 is only acircuit block diagram that is used to introduce some basic componentsthat may be used to practice embodiments of the present invention.Accordingly, the figure is not drawn to scale, nor does the placing ofthe various components imply any sort of actual physical position orconnectivity on a circuit.

In one embodiment of the present invention, the power supply and datainput terminal 110 is a multi-use terminal that can be used differentlyin different modes of the module 100. In a normal mode, the multi-useterminal is used for a single purpose—receiving power, such as aconstant voltage level to power components within the module 100. Incontrast, in a configuration mode, the multi-use terminal 110 is usedfor two purposes—receiving power, as in the normal mode, and receivingdata. The data input over the multi-use terminal 110 may be executableinstructions and/or reference data intended for use during theconfiguration mode and/or the normal mode. For example, the datareceived over the multi-use terminal 110 may be calibration data used tocalibrate raw sensor data output from a sensor integrated with orcommunicatively coupled to the electronic module 100. An electronicsensor module may be configured to reference the calibration data whenprocessing the raw sensor data and output appropriately calibratedsensor data via the output terminal 120 in both the normal mode and theconfiguration mode.

Control circuitry (not shown) in the module 100 controls the operationmode of the module 100. FIG. 2 illustrates a flowchart of a method 200that may be implemented by control circuitry in the module 100 tothereby control the operation modes of the module 100 in accordance withone embodiment of the present invention. The method 200 may beimplemented when the control circuitry is first placed in a known state.For instance, the control circuitry may be configured to automaticallyenter a known reset state in response to receiving a reset signal from apower-on-reset component within the module 100 or a reset pin externalto the module 100. Once the module is placed in the known state, aninitialization routine may be carried out and the module 100 may thenenter a normal mode (stage 210).

While operating in the normal mode, the sensor module 100 carries outits normal or mission mode function(s), e.g., reading, processing, andoutputting sensor data. If, during normal mode operations, a firstpredetermined criterion or set of criteria is satisfied (decision stage220), the module 100 enters a configuration mode (stage 230). Otherwise,the module 100 remains operating in the normal mode (stage 210).

While operating in the configuration mode, the multi-use terminal 110continues to supply a power signal and the module 100 listens for datato be received over the power signal on the multi-use terminal 110. Thereceived data may be, for example, calibration data used to calibrateraw sensor data output from a sensor. In certain embodiments, the module100 may also continue to carry out its normal function(s), e.g.,reading, processing, and outputting sensor data, when operating in theconfiguration mode. If, during configuration mode operations, a secondpredetermined criterion or set of criteria is satisfied (decision stage220), the module 100 returns to the normal mode (stage 210). Otherwise,the module remains operating in the configuration mode (stage 230).

The first predetermined criteria that causes the module 100 to enter theconfiguration mode may be a first predetermined signal level that isapplied from a source external to the module 100 for a firstpredetermined amount of time. Circuitry in the module 100 may beconfigured to recognize the first predetermined signal level applied tothe multi-use terminal 110 (stage 220) to trigger entry into theconfiguration mode (stage 230) after the first predetermined amount oftime. To avoid a false triggering of the configuration mode due to noiseon the multi-use terminal 110, the first predetermined amount of timemay exceed the duration of noise signals that are expected to reach orexceed the first predetermined signal level.

The second predetermined criteria that causes the module 100 to returnto the normal mode (decision stage 240) may include a secondpredetermined signal level that is applied from the external source tothe multi-use terminal 110. The second predetermined criteria may be thesame as or similar to the first predetermined criteria. For example, thesecond predetermined criteria may include detection of the firstpredetermined signal level applied to the multi-use terminal 110 for thefirst predetermined amount of time or for a second predetermined amountof time that differs from the first predetermined amount of time.Alternatively, the second predetermined criteria may include expirationof a countdown timer onboard the module 100 that begins counting downafter the configuration mode is entered. If desired, the module 100 mayalso be configured to enter additional modes in response to otherpredetermined signaling levels or bit sequences input over the multi-useterminal 110. Examples of additional modes include, but are not limitedto, a testing mode, a calibration mode, a programming mode, a start upmode, a verification mode, etc.

FIG. 3 illustrates an electronic sensor module 300 that represents amore specific embodiment of the electronic module 100 of FIG. 1. FIG. 4illustrates a flowchart of a method 400 for controlling the variousoperation modes of the module 300 of FIG. 3 and FIGS. 5A and 5Billustrate graphs 500 a and 500 b, respectively, of signaling levelsversus time at the input and output terminals of the module 300 duringdifferent modes of operation. Accordingly, the module 300 of FIG. 3 willnow be described with frequent reference to the method 400 of FIG. 4 andthe graphs 500 a and 500 b of FIGS. 5A and 5B.

Referring to FIG. 3, the module 300 includes terminals 310, 320, and 330(similar to corresponding terminals 110, 120, and 130 of module 100 inFIG. 1) and vertical ellipses 340 representing additionalnon-data-receiving terminals that are optionally included. The module300 also includes circuitry comprising a controller 340, detectors 344and 346, a sensor 348, and a timer 350. The detectors 344 and 346 areconfigured to receive an input voltage from the multi-use terminal 310and to output detection signals to the controller 340. As will bediscussed in more detail below, the signal detected by the detector 344is a mode selection signal and the signal detected by the detector 346is a configuration data carrying signal, which the controller 340receives from the detector 346 and stores in a data storage unit 352,such as a nonvolatile memory unit, that is communicatively coupled tothe controller 340.

As shown in FIG. 3, the detectors 344 and 346 may include logiccomparators that can compare a received input with a reference voltageV_(ref). Comparators often require a level shifting of input voltagelevels, which can be performed by a high impedance voltage dividernetwork or any similar voltage level shifting circuitry. For example, anetwork of voltage dividing resistors 354 are optionally included in themodule 300 and the values of the resistors are selected to shift theexpected voltage from the multi-use terminal 310 to levels that thecomparators can accurately detect. One or both of the comparators 344and 345 and the voltage dividing resistors 354 of the voltage dividingnetwork collectively comprise circuitry referred to herein as datadetection circuitry.

Referring now to FIG. 4, after power up of the module 300 and a start-upor initialization routine, the module 300 enters a normal mode (stage410). While operating in the normal mode, the sensor module 300 carriesout its normal function(s), e.g., reading, processing, and outputtingsensor data. At any time during normal operations, if the controller 340receives an indication from the detector 344 that a voltage level V_(in)detected on the multi-use terminal 310 is greater than a firstpredetermined level V_(config) for a predetermined amount of time(decision stage 420), the controller 340 causes the module 100 to entera configuration mode (stage 430). Otherwise, the module 300 continues tooperate in the normal mode (stage 410).

Referring now to FIG. 5A, the first predetermined level of voltageV_(config) and a first predetermined amount of time T₁ comprise a firstset of predetermined criteria that governs whether the module 300 entersthe configuration mode. For example, as indicated by the vertical dashedlines and the modes labeled along the horizontal time axis, the module300 enters the configuration mode if a voltage on the multi-use terminal310 remains at or above the first predetermined voltage level V_(config)for the predetermined time period T₁ or longer. The first time period T₁may be measured by the timer 350 and/or a time constant and/orhysteresis lag value, which may be designed into or inherent in theparticular detector used. To avoid a false triggering of theconfiguration mode due to noise on the multi-use terminal 310, the timeperiod T₁ may exceed the duration of noise signals that are expected toreach or exceed the first voltage level V_(config).

With continued reference to the graph 500 a of FIG. 5A, while operatingin the configuration mode, the sensor module 300 listens for data 510 tobe received on the multi-use terminal 110. The received data may becalibration data used to calibrate raw sensor data output from thesensor 348. The configuration data 510 is detected by the detector 346.The configuration data may be communicated by modulating the voltagelevel on the multi-use terminal 310 between the first voltage levelV_(config) and a second voltage level V_(data) that is higher (as shownin the graph 500 a) or lower than the first voltage level V_(config).

As shown in the graph 500 a, the first voltage level V_(config) and thesecond voltage level V_(data) are both higher than a power supplyvoltage V_(dd), but they may instead be lower than the power supplyvoltage V_(dd). One reason for setting the first voltage levelV_(config) and the second voltage level V_(data) higher than the powersupply voltage V_(dd) is to enable the module 300 to remain poweredwhile operating in the configuration mode. Alternatively, one or both offirst voltage level V_(config) and the second voltage level V_(data) arelower than the power supply voltage V_(dd) but high enough to continueto provide sufficient power to the module 300. Consequently, while inthe configuration mode the module 300 may be able to not only writereceived data to the data storage unit 352 but also carry out normalmode operation(s), such as reading, processing, and outputting sensordata 520 via the output terminal 320. Thus, certain embodiments of themodule 300 are capable of full duplex bidirectional communications inthe configuration mode and the controller 340 can carry out the normalfunctions of the sensor module 300 to demonstrate whether the module 300is operating in a calibrated fashion. If the module 300 is not operatingproperly, a new set of calibration data can be transmitted to the module300 as many times as necessary until the data from the output terminal320 satisfies an operator or external automatic test device that themodule 300 has been properly calibrated before entering the normal mode.

Referring again to the method 400 of FIG. 4, if a second predeterminedcriterion or set of criteria is satisfied (decision stage 440), themodule 100 returns to the normal mode (stage 410). Otherwise, the moduleremains operating in the configuration mode (stage 430). The secondpredetermined criteria may include a predetermined data sequence 530detected by the detector 346, which the controller 340 receives and, inresponse thereto, causes the module 300 to return to the normal mode(stage 410). Alternatively, the second predetermined criteria mayinclude a predetermined voltage level, such as the first voltage levelV_(config) or another predetermined voltage level, e.g., between thepower supply level V_(dd) and the first voltage level V_(config). Asanother alternative, the second predetermined criteria may includeexpiration of a second predetermined time period T₂, as illustrated inthe graph 500 b of FIG. 5B. The second predetermined time period T₂ maybe measured by the timer 350. For example, the controller 340 can causethe timer 350 to begin counting down the predetermined time period T₂upon entering the configuration mode.

Referring again to FIG. 3, additional components that may be present inthe sensor module 300 include a voltage regulator 360 and an outputbuffer 362. The voltage regulator 360 may be present if there is a riskthat the overvoltage levels input over the multi-use terminal 310 willoverdrive and therefore damage certain components of the module 300 thatderive power from the V_(dd) voltage on the multi-use terminal 310.Otherwise, the voltage regulator may be omitted to conserve space.Moreover, various components, such as the sensor 348, the timer 350, andthe data storage unit 352 may be external to the sensor module 300. Forexample, in certain applications the sensor 348 is a relatively largeunit and/or is located in a remote region with environmental conditionsthat are hostile to electronic circuitry and therefore cannot easily beincluded in an integrated circuit or circuit board assembly.

FIG. 6 illustrates an electronic sensor module 600 in accordance withanother embodiment of the present invention. The module 600 primarilydiffers from the module 300 in its omission of the timer 350 and thedetector 346. Thus, the module 600 is configured to enter theconfiguration mode without the use of a timer to measure a period oftime that the multi-use terminal 310 is set at or above a predeterminedvoltage level, such as V_(config). Instead, the module 600 is configuredto enter the configuration mode when a unique configuration mode code isasynchronously detected on the multi-use terminal 310. Similarly,another unique code can be designated to signal return to the normalmode after configuration is complete.

FIG. 7 illustrates a graph 700, of signaling levels versus time at theinput and output terminals of the module 600 during different modes ofoperation. As shown in the graph 700, a unique code 710 is transmittedby an external source (not shown), such as a programming module, onmulti-use terminal 310, which the controller 340 receives and recognizesas a signal to enter the configuration mode. Because a unique code isused to trigger the configuration mode instead of a predeterminedvoltage level, such as the first voltage level V_(config), thecalibration data may be received by detecting modulation of themulti-use line between the power supply level V_(dd) and the secondvoltage level V_(data). Moreover, the second voltage level V_(data) maybe lower, e.g., at the level of the first voltage level V_(config).

To implement asynchronous detection of a unique code, an asynchronousreceiver 610, such as a universal asynchronous receiver/transmitter, isincluded in the module 600 to receive the output of the detector 344 andtransmit a serial data stream to the controller 340. The asynchronousreceiver 610 detects a serial data stream input over the multi-useterminal 310. The controller 340 later processes and decodes the serialdata stream to determine if it matches a unique identification code thatis designated to trigger the configuration mode in the module 600. Itwill be appreciated by those of skill in the art, that a protocol and/orhandshaking that is established after the configuration mode is enteredmay be implemented in any of various ways depending on an overall systemarchitecture or how an external data source and the module 600 areconfigured to handle communications.

FIG. 8 illustrates an electronic sensor module 800 in accordance withanother embodiment of the present invention. The module 800 includes allof the circuitry in the module 300 and also includes a set of switches810 that are controlled by a detect enable signal 820 from thecontroller 340. The voltage divider network of resistors 354 consumespower even when not being used. Therefore, in the module 800, the timer350 controls a window of time in which the controller 340 asserts thedetect enable signal 820 and listens to the multi-use terminal 310 forconfiguration data to be received. Assertion of the detect enable signal820 opens the switches 810 to disable the voltage divider network whennot in use. Accordingly, power that would otherwise be dissipated by thevoltage divider network is conserved.

FIG. 9 illustrates a flowchart of a method 900 for controlling thevarious operation modes of the module 800 of FIG. 8 and FIG. 10illustrates a graph 1000, of signaling levels versus time at the inputand output terminals of the module 800 and of the detect enable signal820 during different modes of operation. Accordingly, the module 800 ofFIG. 8 will now be described with frequent reference to the method 900of FIG. 9 and the graph 1000 of FIG. 10.

After a power-up or a reset of the module 800, the module 800 enters aninitialization mode in which a start-up or initialization routine isexecuted and the detect enable signal 820 is asserted (stage 910).During the initialization mode, if the controller 340 receives anindication from the detector 344 that a voltage level V_(in) detected onthe multi-use terminal 310 is greater than a first predetermined levelV_(config) for a predetermined amount of time (decision stage 920), thecontroller 340 causes the module 800 to enter a configuration mode(stage 930). In addition to determining whether to enter theconfiguration mode, the controller 340 determines whether a thirdpredetermined time period (i.e., a configuration time period) T₃ isexpired (stage 922). For example, the controller 340 may instruct thetimer to begin counting down the configuration time period T₃ uponentering the initialization mode and the timer 350 may indicate to thecontroller when the configuration time period expires. If theconfiguration time period T₃ has not expired and the voltage levelV_(in) detected on the multi-use terminal 310 is not greater than thefirst predetermined level the module 800 continues to operate in theinitialization mode (stage 910). If, however, the configuration timeperiod T₃ does expire before the configuration mode is entered, thecontroller 340 causes the module 800 to enter the normal mode andde-assert the detect enable signal 620 (stage 950) without entering theconfiguration mode. Implementing a limited configuration time periodwill save power that would otherwise be dissipated by the network ofvoltage dividing resistors 354.

With reference to the graph 1000 of FIG. 10, while operating in theconfiguration mode, the sensor module 800 listens for data 510 to bereceived on the multi-use terminal 310. The data 510 is detected by thedetector 346 and may be, for example, calibration data used to calibratethe sensor 348.

Referring again to the method 900 of FIG. 9, if, while operating in theconfiguration mode, a second predetermined criterion or set of criteriais satisfied (decision stage 940), the controller 340 causes the module800 to enter the normal mode (stage 950). In the normal mode (stage950), the controller 340 de-asserts the detect enable signal 720 toconserve power and causes the sensor module 100 to carry out its normalfunction(s), e.g., reading, processing, and outputting sensor data.Otherwise, the module remains operating in the configuration mode (stage930). The second predetermined criteria may include a predetermined datasequence 530 detected by the detector 346, which the controller 340receives and, in response thereto, causes the module 800 to enter thenormal mode (stage 950). Alternatively, the second predeterminedcriteria may include a predetermined voltage level or expiration of afourth predetermined time period T₄, as illustrated in the graph 1000 ofFIG. 10.

In an alternative embodiment of the module 800 of FIG. 8, the timer 350is omitted and mode selection is performed without the use of the timeperiods T₃ and T₄. Thus, the module 800 can enter and exit theconfiguration mode at any time, including during normal operations. Forexample, as discussed above, a non-timer-based criteria, such as thepredetermined data sequence 530, may trigger transition from theconfiguration mode to the normal mode.

Moreover, to enable entry to the configuration mode, the detect enablesignal 820 is pulsed or strobed at a periodic interval and a modeselection signal, such as the first voltage level V_(config), or aunique code is detected on the multi-use terminal 310. By strobing thedetect enable signal 820 the module 800 can enter the configuration modeat any time, including during normal operations. Although strobing thedetect enable signal 820 would still dissipate some power byperiodically activating the voltage divider network of resistors 354,some power is also conserved when the detect enable signal 820 isde-asserted.

In an example implementation of the alternative embodiment of the module800, the detect enable signal 820 may be asserted for 10 ms of every 100ms period and the output of the detector 344 is fed to a counter (notshown) that is integrated with or communicatively coupled to thecontroller 340. If after the controller 340 recognizes that a modeselection signal, such as the first voltage level V_(config), isdetected on the multi-use terminal 310 a predetermined number of times,the controller 340 causes the module 800 to exit whatever mode ithappens to be in and enter the configuration mode to listen for datafrom the detector 346. The controller 340 is configured to reset thecounter to zero if the mode selection signal is not detected when thedetect enable signal 820 is asserted to avoid inadvertently triggeringthe configuration mode when noise events coincide with assertion of thedetect enable signal 820. This inexpensive implementation of modetransition simulates a low pass filter of the signal on the multi-useterminal 310. The analog of this digital simulation of low passfiltering is an RC filter, which would typically consume much more chiparea.

FIG. 11 depicts a graph 1100 of signaling levels versus time at inputand output terminals and of the detect enable signal 820 duringdifferent modes of operation of the timerless embodiment of the module800. As shown in the graph 1100, the detect enable signal 820 is strobedat regular intervals depicted by a series of pulses 1110 and 1120. Attime T₅ an external source applies the first voltage level V_(config) toinitiate transition to the configuration mode. The controller 340detects the first voltage level V_(config) at each of a series ofconsecutive pulses 1120 of the detect enable signal 820, which brieflyenable detection by the detectors 344 and 346. If the first voltagelevel V_(config) is detected a sufficient number of consecutive times(e.g., about three times to about twenty times depending on expectednoise levels) the controller 340 causes the module 800 to enter theconfiguration mode. As shown in the graph 1100, the controller 340asserts the detect enable signal 820 for the duration of theconfiguration mode to enable receipt of data by the detector 346.

By using a multi-use terminal to receive calibration data and power on asensor module, the relatively small interface of the sensor module isused effectively for multiple operations in multiple modes andcalibration can be performed quickly. Moreover, preserving the dataoutput terminal for the sole purpose of outputting data minimizes theamount of extra hardware needed on the module to receive calibrationdata, enables full duplex bidirectional communications during theconfiguration mode, and increases communication speeds. Furthermore, thesensor modules described herein add only a few small, low-powerconsuming components to standard sensor modules to perform calibrationfunctions. For example, the sensor modules described herein do notrequire integration of high power/low speed driving circuitry, which isincluded in certain other implementations to output data over the powersupply terminal due to the significant amount of capacitance typicallyimplemented on the power supply terminal. Instead, high power drivingcircuitry may only be needed in a test or programming system that isexternal to sensor modules of the present invention.

The foregoing detailed description of various embodiments is provided byway of example and not limitation. Accordingly, the present inventionmay be embodied in other specific forms without departing from itsspirit or essential characteristics. For example, although the foregoingdescription is directed to sensor modules, any module or circuit thathas a limited number of terminals (or for which a reduced numbers ofterminals is desired to decrease interface complexity, for example) anda need to receive data for configuration, testing, upgrading firmware,or any other purpose for which input data or instructions is needed orexpected to be needed at startup only and/or at relatively infrequentintervals during operation can benefit from the principles of theinvention. Examples of such alternative modules include, among otherthings, a motor speed controller module, which may require an input atstartup or during normal operation of a target speed to be maintained,an environmental parameter controller module, which may require an inputat startup or during normal operation of a target environmentalparameter to be maintained, or a data logger, which may require an inputat startup or during normal operation of a desired parameter to belogged, an enable/disable setting, or the like.

Moreover, one of ordinary skill in the art will appreciate that thenotation of V_(dd) for the power supply voltage is exemplary and is notintended to limit implementation of the invention to one in which poweris supplied to drain terminals of field effect transistors.Implementations that use bipolar junction transistors, for example, arealso contemplated.

The described embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A sensor module, comprising: a voltage dividernetwork having a first node, a second node, and a third node; a firstdetector having a first input terminal, a second input terminal, and anoutput terminal, the first input terminal of the first detector coupledto the first node and the second input terminal of the first detectorcoupled for receiving a first reference voltage; a controller having afirst input terminal, a second input terminal, and a first outputterminal, the first input terminal of the controller coupled to theoutput terminal of the first detector; a second detector having a firstinput terminal, a second input terminal, and an output terminal, thefirst input terminal of the second detector coupled to the second nodeand the second input terminal of the second detector coupled forreceiving a second reference voltage and the output terminal of thesecond detector coupled to the second input terminal of the controller;a first transistor having a control terminal, a first current carryingterminal, and a second current carrying terminal, the first currentcarrying terminal of the first transistor coupled to the first inputterminal of the first detector and the second current carrying terminalof the first transistor coupled to the first node; a second transistorhaving a control terminal, a first current carrying terminal, and asecond current carrying terminal, the first current carrying terminal ofthe second transistor coupled to the first input terminal of the seconddetector and the second current carrying terminal of the secondtransistor coupled to the second node; a third transistor having acontrol terminal, a first current carrying terminal, and a secondcurrent carrying terminal, the control terminal of the third transistorcoupled to the control terminals of the first transistor and the secondtransistor and to a third output terminal of the controller, the firstcurrent carrying terminal of the third transistor coupled to the firstterminal of the second detector through a resistor, and the secondcurrent carrying terminal of the third transistor coupled for receivingthe first source of potential; a voltage regulator having an inputterminal and an output terminal, the input terminal of the voltageregulator coupled to the third node, and the output terminal of thevoltage regulator coupled to the third input terminal of the controller;and a buffer having an input and an output, the input of the buffercoupled to the first output terminal of the controller and the output ofthe buffer serving as a data output terminal of the sensor module. 2.The sensor module of claim 1, further including an asynchronous receivercoupled between the output terminal of the first detector and the firstinput terminal of the controller.
 3. The sensor module of claim 1,wherein the voltage divider circuit comprises a resistor divider networkincluding: a second resistor having a first terminal and a secondterminal, the first terminal of the second resistor coupled to the inputterminal of the voltage regulator to form the third node, wherein thethird node serves as a multi-use terminal of the sensor module that isconfigured for receiving calibration data from a source external to thesensor module and receiving power; a third resistor having a firstterminal and a second terminal, the second terminal of the firstresistor coupled to the first terminal of the third resistor to form thefirst node.
 4. The sensor module of claim 1, wherein the first detectorcomprises a first comparator having a noninverting input terminal, aninverting input terminal, and an output terminal, the noninverting inputterminal of the first comparator serving as the first input terminal ofthe first detector and the inverting input terminal of the firstcomparator serving as the second input terminal of the first detectorand the second detector comprises a second comparator having anoninverting input terminal, an inverting input terminal, and an outputterminal, the noninverting input terminal of the second comparatorserving as the first input terminal of the second detector and theinverting input terminal of the second comparator serving as the secondinput terminal of the second detector.
 5. The sensor module of claim 4,wherein the controller further includes a first input/output terminal, asecond input/output terminal, and a third input/output terminal, andwherein the sensor module further includes a sensor coupled to the firstinput/output terminal of the controller, a data storage element coupledto the second input/output terminal of the controller, and a timercoupled to the third input/output terminal of the controller.